Paper webs may be manufactured using a variety of devices, such as suction breast roll formers, twin wire formers, crescent roll formers, or the like. While the aim of paper forming equipment is generally to produce a uniform sheet in both the machine and cross-machine directions, each type of former has particular advantages and disadvantages.
The trend in tissue manufacturing is to produce a sheet with a machine direction (MD) strength to cross-machine direction (CD) strength (MD/CD ratio) that is close to 1.0 to make the most efficient use of fibers to generate strength in the sheet. This is particularly necessary in products that are used by the consumer in various orientations where the overall strength of the sheet becomes the weaker of the MD strength or CD strength.
One disadvantage associated with suction breast roll formers is a high degree of variability in formation depending on the location and operating parameters of the headbox. While suction breast roll formers are generally good at operating at one set of conditions, less than optimal operating conditions produce less than optimal sheet formation. Typical defects in a tissue sheet produced with a suction breast roll former are intermittent machine direction streaks randomly oriented on the surface of the sheet. Sheet defects of this type tend to raise the MD/CD ratio of the sheet.
There is more demand in the competitive tissue market to have tissue machines that are able to make a variety of products on the same machine to make best use of the
equipment available. The ability of tissue machines to operate over a wider range of process conditions is becoming more important.
Therefore, what is lacking and needed in the art is an improved suction breast roll former which maintains consistent web formation over a wider range of operating conditions than is presently achievable. What is also lacking and needed is an improved suction breast roll former that can readily be constructed as a retrofit of current suction breast roll formers.